As described in said patents and publication, upon receiving notice of the unauthorized movement of an owner's vehicle equipped with such a “LoJack” or similar system, the owner so notifies the police or other recovery authority to put in operation dedicated radio network transmitters for querying vehicle-installed transponders that then become activated to transmit radio-tracking signals to police or other recovery vehicles for tracking the stolen vehicle and recovering of the same.
Systems for automatically sensing the unauthorized tampering, use, or more generally the movement of the vehicle include, for example, those described in U.S. Pat. No. 5,917,423 of said assignee. Systems For Aiding The Alerting Of The Owner Of The Vehicle Of Its Theft—so-called “uplink” notification—are also described in said assignee's PCT application PCT/GB 97/01444 published on or about May 25, 2000.
While the above-referenced radio tracking techniques are widely and highly successfully in use, permitting recoveries by the police in up to about a few hours or so on the average, it is the delay in notifying the owner of the vehicle theft, so as to put the recovery technique in motion, that is the weak link in the recovery process. There is, moreover, an economic limit on the feasible number and locations of dedicated vehicle recovery radio networks (generally of VHF frequencies), and thus a relatively limited geographic area for alerting and recovery. The present invention, however, uses existing widely geographically spread cellular telephone radio networks (UHF frequencies) as supplement to the limited radio recovery networks to enlarge the effected area of recovery activation, both in terms of notification of vehicle theft and in providing rough or coarse location of the zone in which the stolen vehicle is present, and then the facility to bring the tracking vehicle into that zone for fine tracking by the “LoJack” or similar recovery system.
A fundamental issue that the concept of the invention addresses is how to activate a stolen vehicle transponder when the vehicle is out of its “home” recovery network coverage area and frequency, and is, indeed, in a wide coverage area where other radio networks exist (as for other uses, such as cellular telephone) that have completely different frequencies. The invention teaches how to supplement the limited coverage area of the vehicle recovery transmitter network with the facilities of the widely geographically existing cellular radio telephone networks and in a novel manner that extends the activation and tracking capabilities of the recovery network. This is effected by equipping the vehicle not only with a VHF transponder responsive with code to the radio recovery network transmitter queries, but also a vehicle-equipped cellular telephone frequency transceiver, responsive also with identification to the cellular radio network query. The site of the cellular radio network receiving the vehicle transceiver reply thus identifies itself to the control center (coarse location) which enables the tracking vehicle to proceed into that area locally and either with the cooperation of the radio recovery network transmitter if within range, or by carrying a local radio recovery transmitter in the recovery vehicle, activating the vehicle transponder to enable tracking of the stolen vehicle locally.